2000年夏季莱州湾主要观测要素的分布特征

在 2 0 0 0年夏季莱州湾加密大面调查资料的基础上 ,研究了莱州湾海域海水的温度、盐度、溶解氧、浊度、叶绿素、无机氮、磷酸盐和硅酸盐的分布特征 ,初步讨论了它们之间的相互关系。结果表明 ,莱州湾盐度值与以前相比有显著升高 ;叶绿素南部的高值区对应于溶解氧的低值区 ,温度的高值区 ;浊度受黄河径流的影响较大 ;无机氮西部浓度高 ,东部浓度低 ,且相差很大 ;浮游植物生长的限制因素东部与西部海域不同 ,东部为氮限制 ,而西部为磷限制。     

INFLUENCE OF THE SURFACE AIR TEMPERATURE OVER ASIAN-PACIFIC REGION ON THE SUMMERTIME NORTHEASTERN ASIAN BLOCKING HIGH*

Synthesis analysis and singular value decomposition (SVD) methods were used to study the impact of surface air temperature (SAT) over Asian-Pacific region on the summertime northeastern Asian blocking high (NABH) with NCEP/NCAR Reanalysis Data.The results showed that 500 hPa geopotential height and SAT fields over Asian-Pacific region shared the similar pattern of East Asian Pacific (EAP) wave train;there was steady remote response relationship between the EAP wave train in summer and the "+-+" pattern of tropical SAT in zonal direction from former winter to summer;there were two relative negative(positive) Walker circulations over the tropical Indian Ocean and Pacific when being more(less) summertime NABH. The influence of sea surface temperature anomaly (SSTA) on the summertime NABH was possibly as follows.The special distribution of SSTA in tropical zonal direction continuously forced the tropical convection and zonal circulation from former winter to summer,and led them to act anomaly.Finally the abnormal conditions were transported to middle-high latitudes through EAP wave train and yielded the advantageous or disadvantageous atmospheric circulation background for the summertime NABH.     

渤海夏季环流和渤海海峡水体输运的数值诊断研究

建立了一个基于POM的涵盖渤、黄、东海的海洋环流诊断模式来研究渤海夏季环流。分别进行了风海流、密度流和总环流的模拟。从模拟结果得出:渤海海峡夏季与北黄海的水交换总的来说表现为北进南出特征,但与冬季相比,其流量较小(约5×103m3s 1)且不能深入渤海。辽东湾基本上受气旋式环流控制,黄河口外至渤海湾受反气旋式环流控制。数值实验表明,渤海夏季主要属密度流性质。在渤海海峡的北岸存在一支明显的上升流,而且北部的海水垂向运动比南部要强许多。在渤海中部的纬向断面上,东部的海水垂直交换要比西部活跃得多;渤海海水的垂向运动亦主要是密度流导致的。     

山东夏季气温年际变化形成的气候特征

为研究本地区短期气候预测方法,利用山东80个代表站夏季平均气温、降水量资料和NCEP／NCAR月平均再分析资料(1961～2001年),分析了夏季平均气温年际变化的气候特征、冷暖夏的环流形势及夏季风与气温的关系。结果表明：EOF第一模态几乎反映了整个温度场的时空变化特征;夏季气温标准化距平年际变化显著,有弱线性增温趋势;极端冷、暖夏大气环流形势差异明显,显著差异区在亚欧一北太平洋地区,冷夏年中高纬度欧亚大陆存在正欧亚一太平洋(EUP)型遥相关,东亚地区有负太平洋-日本(PJ)型波列,暖夏年反之。东亚夏季风强弱与山东夏季气温关系密切,强(弱)夏季风时,易造成山东暖(冷)夏;同期降水对气温有负反馈,对气温升高有一定的抑制作用。     

Persistence of Summer Sea Surface Temperature Anomalies in the Midlatitude North Pacific and Its Interdecadal Variability

The present study investigates the persistence of summer sea surface temperature anomalies(SSTAs) in the midlatitude North Pacific and its interdecadal variability. Summer SSTAs can persist for a long time(approximately 8–14 months)around the Kuroshio Extension(KE) region. This long persistence may be strongly related to atmospheric forcing because the mixed layer is too shallow in the summer to be influenced by the anomalies at depths in the ocean. Changes in atmospheric circulation, latent heat flux, and longwave radiation flux all contribute to the long persistence of summer SSTAs. Among these factors, the longwave radiation flux has a dominant influence. The effects of sensible heat flux and shortwave radiation flux anomalies are not significant. The persistence of summer SSTAs displays pronounced interdecadal variability around the KE region, and the variability is very weak during 1950–82 but becomes stronger during 1983–2016. The changes in atmospheric circulation, latent heat flux, and longwave radiation flux are also responsible for this interdecadal variability because their forcings on the summer SSTAs are sustained for much longer after 1982.     

副高、极涡因子对我国夏季降水的影响

利用奇异值分解方法(SVD)分别分析了北半球副高指数和北半球极涡指数对我国夏季降水(6～8月)的影响,并详细讨论了对我国夏季降水影响重大的具体关系,以及它们影响的区域情况.研究发现,我国夏季降水主要受前期冬季极涡强弱的影响.冬季副高因子的影响是半球范围的,而春季副高因子的影响主要取决于我国南部的副高系统.综合研究极涡、副高两者对我国夏季降水的影响要比分别研究它们各自的影响所得模态的代表性好,预报价值也更高.     

近50年长江中下游地区夏季气温变化与环流异常

Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River (MLRYR) and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River (MLRYR). Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating (cooling) caused by the vertical thermal advection as well as the diabatic heating (cooling) caused by diabatic processes can explain the formation of the high (low) temperature events in the middle and lower reaches of the Yangtze River (MLRYR) in boreal summer.     

Summertime temperature variations in the middle and lower reaches of Yangtze River and their related circulation anomalies in the past five decades

Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River (MLRYR) and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River (MLRYR). Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating (cooling) caused by the vertical thermal advection as well as the diabatic heating (cooling) caused by diabatic processes can explain the formation of the high (low) temperature events in the middle and lower reaches of the Yangtze River (MLRYR) in boreal summer.     

近50年长江中下游地区夏季气温变化与东半球环流异常

采用中国气象局整编的气温资料以及NCEP/NCAR再分析资料,分析了1960-2005年中国长江中下游地区夏季气温变化与东半球环流异常的联系.结果表明:近50年来,中国长江中下游地区夏季气温呈现出明显的非对称趋势变化特征,夏季气温的上升趋势在很大程度上是日最低气温上升带来的结果;典型高、低温年,在环流场的垂直分布均呈准正压结构的情况下,从对流层低层一直到高层,东半球大部分区域的异常值符号相反.此外,出现在江淮流域上空的异常环流的形成和维持可能与三支不同源头的波列有关;地面长波辐射对气温的影响在夜间超过白天,气温分别与感热通量和潜热通量呈负相关以及正相关关系;典型高(低)温年,垂直温度平流引起的异常动力增(降)温和非绝热加热引起的异常增(降)温可以作为解释高(低)温年气温异常维持的原因.     

Intercomparison of the Summertime Subtropical High from the ERA-40 and NCEP/NCAR Reanalysis over East Eurasia and the western North Pacific

An intercomparison of summertime (JJA) subtropical geopotential heights from the ERA-40 and NCEP/NCAR reanalysis is specifically conducted over East Eurasia and the western North Pacific. The NCEP/NCAR is obviously lower than the ERA-40 in the mid-to-lower troposphere in most regions of East Eurasia before the mid-1970s, but becomes higher than the ERA-40 after the mid-1970s and thus demonstrates stronger increased trends during the period of 1958--2001. Both reanalyses are lower than the observations in most regions of China. The NCEP/NCAR especially shows tremendously systematic lower values before the mid-1960s and displays abrupt changes before the 1970s. Several indices of the western North Pacific subtropical high (WNPSH), calculated from both reanalyzed summer geopotential heights, also reveal that the variation trend of the NCEP/NCAR is stronger than that of the ERA-40 in the mid-to-lower troposphere from 1958 to 2001. Through singular value decomposition (SVD) analysis, the summer geopotential heights at 500 hPa from the ERA-40 are better than the NCEP/NCAR counterparts at interacting with the precipitation over the East Asian monsoon region. The results indicate that the NCEP/NCAR in the mid-and-lower troposphere may overestimate interdecadal changes and should be used cautiously to study the relationship between the WNPSH and precipitation ove ther East Asia Monsoon region before the mid-1970s.